following on from my posts on the Canopus bug here and here I referred to another thread on the Digidesign User Conference about jerky video playback.

Well a guy (bedubya) has posted here a very comprehensive report on tests he has undertaken in his facility so here it is…

I work at a large studio and I have done extensive testing on this problem being that we are seeing it consistently.  I have used a G5 with PT7.4 as a dedicated pic playback device without issue for many years.

We decided to turnover one of our stages completely to PT8 using Satellite to latch everything up, but when we went to play picture (wild, no Satellite) after freshly installing 10.5.8 (subsequently 10.6.2), all flavors of PT 8.0cs3-8.0.3cs1, we noticed the stuttering video cadence.

We reverted back to 10.4/7.4cs10 and playback was smooth playing wild as well as latched up to timecode.  I decided to up the ante and installed a brand new Quad core 2.66 Mac Pro with PT8.0.1cs1 (subsequently 8.0.3cs1) on Snow Leopard (shouldn’t work, but it does) and video playback was consistently stammering.  After reading all of the various threads on this user conference, I started trying everyone’s suggestions.

The only thing that proved helpful was the Quartz Debug app. This helped explain everything… Leopard defaults the “beam synchronization” to automatic which would explain why when testing we could run the video a few times with no issue and then it would look really awkward for the next few playbacks.  Forcing the beam sync on causes an exaggerated playback stutter and disabling it altogether let the video payback without stutter BUT(!) it causes a tear horizontally across the frame at fast pan or travelling motion through the frame. It definitely is night and day performance from enabled to disabled beam syncronization, but the tear is not acceptable either.

I used four distinctly different CPU’s (older to brand new out of the box)… a PCI-x G5 w/ATI video card, a PCI-e G5 w/NVidia video card, an older Mac Pro Quad w/ATI video card, and a brand new Mac Pro Quad w/NVidia card.  The PCI-x CPU works with 10.4/PT7.4 very smooth playback, but same hardware with 10.5/PT8.0-8.0.3cs1 stutters.  We use DVCProHD 1080 that we generate ourselves from Avid DNx source files for most of our stage playback with some DV for standard def.  Same hardware and video files that work in 10.4/PT7.4 do not work when that system is running 10.5 or 10.6 and PT8.  I have spent an entire week going through all of the motions and confirming and reconfirming the symptoms.

I can tell you that there is something wrong with how graphics in Leopard works.  It’s very real.  the best way to test this is to look at film company logos, ie, Universal, Fox, WB logos.  Travelling panning shots look horrific.  And I’ve tried it all… lower resolutions, hiding the ProTools windows, hanging the video window over the edge of the main screen, using actual size instead of filling the screen with video window, creating boot drives of various combos of Mac OS and PT, video cards, video window on main screen, various codecs (older and newer versions), Intensity Pro card… everything everyone here has suggested.  Quartz Debug almost nails it if not for the tear.

I have a test bed set up at my desk and I have resources if anyone has any suggestions (good ones) to try.  This is critical to our business and needs a quick resolution as our clients would like to see the video they provide play properly on a 30′ wide screen when the director and producers show up.  Hopefully the alarm bells are ringing there at Digi because they are ringing here on the lot.

Comments (1):

1. 

   Mike Thornton said:
   March 28, 2010 at 9:44 am

   Digidesign Tech Support have recently posted…

   We’re working closely with Apple on this issue and, yes, it’s definitely high-priority.